Certification
What does NACE MR0175 / ISO 15156 compliance actually require?
It requires that the material, its hardness, its heat treatment condition and its cold work level are all qualified for the specific partial pressure of H2S, chloride content, pH and temperature of your service. It is a service-specific qualification with documented hardness limits, not a grade label a mill can simply stamp on.
NACE MR0175 / ISO 15156 governs materials for H2S-containing oil and gas production. Compliance is conditional, and the conditions are what buyers most often miss:
- The environment must be defined. Partial pressure of H2S, chloride concentration, in-situ pH, temperature and the presence of elemental sulphur all change which materials are acceptable. 'Sour service' on its own is not a specification.
- Hardness is capped, typically 22 HRC for carbon and low alloy steels, and the cap applies to the weld and heat affected zone as well as the parent metal. The certificate must report actual hardness readings.
- Heat treatment condition is part of the qualification — normalised, or quenched and tempered, as stated in the relevant part of the standard. A grade acceptable as Q+T may not be acceptable as rolled.
- Cold work is limited on austenitic and duplex grades, which is why cold drawn or heavily cold formed items need re-solution annealing to remain compliant.
Part 2 covers carbon and low alloy steels, Part 3 covers corrosion resistant alloys and lists them by environmental limit. For duplex, the standard also sets a PREN floor and a ferrite balance range.
When enquiring for sour duty, send the environment data with the grade and form. Axicor arranges NACE-qualified supply with hardness reporting and, where asked, HIC testing to NACE TM0284 and SSC testing to TM0177.
Grades referenced
Need this confirmed for your job?
Send the duty, the size and the certification you need. We answer with a grade, a stock position and a price — not a brochure.
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